Tuesday Montebello, East 56th’s longtime neighborhood restaurant with elegant regulars, no loud music, quiet excellent service, was startled by Joan Rivers’ table. Gleeful screeches. March 29, “Joan & Melissa’s” WE tv show, features Joan — who predates the pyramids — doing porn. The stud’s Ray J, who made Kim Kardashian’s sex tape more famous than the original Big Bang.

Joan: “We’re in bed. Under the covers. He’s naked. A sheet’s around me. Lighting’s dark. I got waxed every place — under arms, over legs. Only my eyelashes remain. Fingernails, toenails done, coif done. So much lotion on me that I nearly slipped out of bed. Breath mints. “He did so many things to me that Kim and I now have a special bond.”

Nice. But why do such a crappy thing?

“Because it’s our fourth season, and every year you have to take it down a watt.”

After Joan gets dressed, her seven-room Connecticut furnishings of 12 years — including what Sondheim and Clive Davis plopped on — get auctioned April 1. The Frank Lloyd Wright house (near Milford if you’re poor; near Washington if you’re rich) is across from Anne Bass, down from Barry Diller, a hum away from Patti LuPone. Mick Jagger had rented it, “but I removed the Jacuzzi because who knows whose ass was there.”

Christie’s half-a-mil sale will redo a bedroom in another of her homes.

Where’s Wladimir?

Hayden Panettiere’s fiancé is 10-foot Ukrainian world heavyweight champ Wladimir Klitschko, whose hands covered my living room. His brother, Vitali, standing with their pro-West president Viktor Yushchenko, once told me: “Wladimir, also boxer. Better than me. I support him with all my energy. After him I start. Problem is no french fries. For me, talk is food.”

Then: “I heading to be mayor of hometown Kiev. Someday maybe president. Is cliché that fighters are stupid. Like all politicians are liars. But true all journalists make intrigue.”

He had two giant backups along as protection against me. Now in Parliament, a leader of the Ukraine main opposition party, why aren’t we hearing from both brothers now? How busy can Wladimir be with Hayden?

Star outfitted

Kim Novak, the Jennifer Lawrence of the ’50s and ’60s, decorated the recent Oscars. Problem? Who’d furnish her clothes. Several designers ducked.

Reem Acra graciously offered. Emerging from her Carmel home, she’d have a white sequin wrap gown. Dieting three days, nixing borrowed jewels, on Wednesday she suddenly chose something Columbia Pictures made for her 20 years ago.

And after the whole hoo-hah was over? Kim felt her co-presenter Matthew McConaughey did not treat her well backstage.

Jackie O about heiress Bunny Mellon, who just left us at age 103: “If I had a choice, for my daughter-in-law I’d have liked an Audrey Hepburn who played a princess, a Grace Kelly, who became a princess, or a Biddle, a Duke, a Phipps, an Astor or a Bunny Mellon who lived like a princess.”